Stealthy approaches can be handled with other systems. I would argue that they need to be because I may want to make a stealthy approach from some distance far greater than conventional drives could accomplish in a reasonable amount of time. So I’d want stealth even while in warp.
I’d argue that sensors are active, so if you want to see, you have to be seen. And if you don’t want to be seen, you can’t see. Pick your level of seeing and being seen to fit the circumstances.
Essentially, you’re carrying a flashlight at night. You can see and be seen based on the power of that flashlight.
All manner of high speed attack would be lost, certainly (barring any weapons that can be released while on warp).
The question is whether high relative attack speeds add anything to engagements. They clearly add a dimension of skill and variety for the attackers, but if the defenders can’t do anything but sit and let their shields absorb the hits then it’s not much of a gameplay mechanic. It would work well in a single player or PvE game, but I’m not so sure about a PvP game.
What would be the counter to the high speed attack?
Also, all high speed attacks would have to be balanced such that nobody can just skate across the thruster/warp boundary while attacking. That is, warp at 2000m/s towards a target, drop to 1999m/s, drop a bomb, then go back to 2000m/s and resume on warp.
That’s not really an issue. If I say that I’m on thrusters up to 1000m/s and on warp above that, and both are newtonian, then it doesn’t matter which one I’m using when involved in straight movement scenarios. If the networking code can tolerate 5000m/s ships flying side by side, then Carriers can launch and recover ships at up to 5000m/s. At low speeds, they’ll be on thrusters. At higher speeds, they’ll be on warp.
Note that the warp prototype could handle all ship interactions between 0 and 50c absolute speed and 0 and 3km/s relative speed.
And while I’m daydreaming, what happens when warp interdiction becomes a thing? If I’m automatically put into warp at 1000m/s and I’ve been warp interdicted, surely I’m going to just keep firing my thrusters and keep going as Battlescape operates today. So any areas of warp interdiction are going to need to deal with high speeds combat. Unless thrusters just don’t go faster than 1000m/s (suggesting that thrusters aren’t rockets, but some other technology).